Ahead of the 2020 sulphur cap many shipowners have not decided yet which measure they will take in order to comply with the regulation: installation of scrubbers or adoption of low sulphur fuels.

Many shipping companies, such as Maersk, Hapag Lloyd and Klaveness, will adopt low sulphur fuels, while some fuel companies are to sell a more expensive, 0.5% sulphur product, while hoping for low numbers of scrubber installation. However some operators claim that installing scrubbers is the cheapest option.

Scrubbers, however, are not a perfect solution, Clean Arctic Alliance says. "From 2020, IMO regulations dictate that fuel must have a maximum of 0.5% sulphur content. Ship operators will need to either switch to low sulphur fuel, or use a scrubber to remove the SOx from the exhaust gas. While switching to low-sulphur fuel deals with the problem of air emissions, scrubbers are an end-of-pipe technology, which produces a residue from the cleaning process that needs to be disposed of and there is concern that scrubber residue and wash-water could end up being dumped in the ocean."

Concerns regard the availability of low sulphur fuels as well. According to however, the required volumes of low-sulphur fuel will be available for the world fleet from 2020.

As well as reducing SOx emissions, a switch by all ships from heavy fuels to lighter or distillate fuels can reduce black carbon (BC) by more than half, but the reductions will be lower if ships switch from residual fuels to blends of residual and lighter fuels.

The switch from HFO to distillate fuel means minimal or no technical intervention on ships, so switching fuels can be conducted by the existing fleet. Enforcement of the sulphur regulation would also be simpler when using low-sulphur fuel, since ships will not need to carry fuels with a higher sulphur content than 0.5%.